Two sound sources emitting sound each of wavelength `lambda` are fixed at a given distance apart. A listener moves with a velocity `u` along the line joining the two suorces. The number of beats heard by him per second is

Options

A. `(2u)/(lambda)`
B. `(u)/(lambda)`
C. `(u)/(3lambda)`
D. `(2lambda)/`

Answer

A

Explanation

frequency heard by listener
`n_(1) = (v - u)/(V)(V)/(lambda) , n_(2) = (V + u)/(V)(V)/(lambda)`

beat frequency `= n_(2) - n_(1) = (2u)/(lambda)`